Polytetrafluoroethylene (PTFE) Femorodistal Grafts with a Distal Vein Cuff for Critical Ischaemia

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1 Eur J Vasc Endovasc Surg 15, (1998) Polytetrafluoroethylene (PTFE) Femorodistal Grafts with a Distal Vein Cuff for Critical Ischaemia L. D. Wijesinghe ~, D, M. Beardsmore and D, J. A. Scott Department of Vascular and Endovascular Surgery, St James's University Hospital, Leeds, U.K. Objective: To analyse the results of PTFE femorodistal bypass grafts using a distal anastomotic vein cuff in the treatment of critical ischaemia. Design: Prospective study of consecutive patients under the care of a single Vascular Surgeon. Setting: A dedicated Vascular Surgical Unit in a University teaching hospital. Subjects: Fifty-one consecutive femorodistal PTFE grafts were performed on 50 patients (median 74 years, range years, 25 men; median ankle:brachial index 0.4). In 28 (55%) a common ostium arteriovenous fistula (A VF) was fashioned at the distal anastomosis. Results: The 30-day postoperative mortality was 8%, with (21%) major complications. The 1 and 2 year primary patency was 64% and 51%, respectively, with corresponding limb salvage rates of 85% and %. The presence of an A VF did not signi~'cantly affect graft patency or patient survival, but appeared to hinder limb salvage. The latter effect may be due to bias in patient selection. Conclusion: PTFE femorodistal grafts with a distal vein cuff are a suitable alternative to autogenous saphenous vein in distal reconstructions for critical ischaemia. No conclusions can be made about the efficacy of an A VF in this context. Key Words: PTFE; vein cuff; critical ischaemia. Introduction Autogenous saphenous vein (ASV) has remained the conduit of choice for arterial bypasses in the leg since its introduction by Kunlin in 1949,1 and in its absence, arm vein achieves satisfactory patency rates. 2 When no suitable venous conduit is available, a prosthetic graft such as PTFE is an alternative. While the patency rates for PTFE grafts to the above-knee popliteal artery compare favourably with those for ASV grafts, 3 the same cannot be said for more distal bypasses, especially those required for critical ischaemia or limb salvage surgery. 3'4 Several arguments have been proposed to explain the lower patency rates of prosthetic grafts, including the higher flow rates required to prevent thrombosis in PTFE, 5 progression of more distal disease 6'7 and the development of neointimal hyperplasia at the distal anastomosis. 8"9 The effect of the latter may be mitigated *Please address all correspondence to: L. D. Wijesinghe, Department of Vascular and Endovascular Surgery, St James's University Hospital, Beckett Street, Leeds LS9 7TF, U.K. by the incorporation of a vein cuff at the distal anastomosis of a PTFE graft. A randomised study by the Joint Vascular Research Group 1 has shown no difference in patency rates between cuffed and uncuffed PTFE bypasses to the above-knee popliteal artery. However, in the belowknee position the cuffed grafts achieved a significantly better patency rate. The number of distal bypasses in the trial was too small to allow meaningful analysis, but it would seem reasonable to assume that the beneficial effect of the vein cuff would extend to the smaller tibial and peroneal arteries where a direct PTFE to vessel anastomosis is technically more difficult. Raptis and Miller support this hypothesis with a 12-month patency of % for primary femorodistal PTFE grafts with cuffs for limb threatening ischaemia. 11 This figure was significantly better than the patency of uncuffed distal grafts. This paper reports the results of femorodistal PTFE grafts covering a mixture of primary, secondary and tertiary procedures in which no suitable venous conduit was available. All bypasses were carried out for critical ischaemia as defined by the Second European /98/ $12.00/ W.B. Saunders Company Ltd.

2 450 L.D. Wijesinghe et al. Table 1. Distribution of risk factors according to ISCVS/SVS criteria. Risk factor Cardiac status 0 Asymptomatic, normal ECG 25 (50) 1 Asymptomatic, remote or occult MI () 2 Stable angina, controlled ectopy 11 (22) 3 Unstable angina, symptomatic ectopy, 4 (8) MI<6 months ago Diabetes 0 None 37 (74) 1 Adult onset, diet controlled 9 (18) 2 Adult onset, insulin controlled 4 (8) 3 Juvenile onset 0 (0) Tobacco use 0 None for last years 34 (68) 1 None current, smoked in last years 3 (6) 2 Current, less than one pack/day 11 (22) 3 Current, more than one pack/day 2 (4) Hypertension 0 None 38 (76) 1 One-drug controlled 9 (18) 2 Two-drug controlled 3 (6) 3 Needs more than three drugs, uncontrolled 0 (0) Carotid disease 0 No symptoms, no bruit 42 (84) 1 Asymptomatic but with evidence of disease 1 (2) 2 Transient ischaemic attack 5 () 3 Stroke 2 (4) Hyperlipidaemia 0 Cholesterol/triglycerides within normal 42 (84) limits 1 Mild elevation, diet control 6 (12) 2 Types IL III and IV, strict diet 0 (0) 3 Diet and drug control 2 (4) Number of patients (%) Consensus Department 12 and were constructed with a distal anastomotic vein cuff. Patients and Methods Patient details Fifty-one consecutive femorodistal PTFE grafts were performed on 50 patients (median 74 years, range years, 25 men) between December 1993 and January All patients had critical ischaemia as defined by the European Consensus Document. ~2 Thirty-seven (73%) had rest pain alone and 14 (27%) had a combination of rest pain and tissue loss. The median ankle:brachial pressure index at rest was 0.4 (interquartile range ) and the median isotope limb blood flow was 2.12 ml / ml/min (interquartile range ), the low normal value being ml/ ml/min. ~3 Patients' risk factors were recorded prospectively according to ISCVS/SVS recommendations ~4 and are detailed in Table 1. All patients were prescribed a daily dose of 75 mg aspirin and enrolled in a duplex graft surveillance programme. Patients noted to have been lost to follow-up were recalled for graft assessment. Operative details All procedures were carried out by a single Consultant Vascular Surgeon (DJAS) working in a dedicated Vascular Surgical Unit of a University teaching hospital. A standard technique was employed involving a combination of general and epidural anaesthetic. Broadspectrum antibiotic cover was instituted at the induction of anaesthesia and continued for three postoperative doses. Five thousand units of heparin were administered intravenously before the application of vessel clamps. In all cases the graft used was 6ram diameter externally supported PTFE (Impra, Arizona, U.S.A.). Having tunnelled the graft, an exsanguinating Esmarch tourniquet was applied to allow a bloodless operating field at the distal anastomosis while avoiding the use of clamps on small calf vessels. A common ostium AVF was fashioned to a vena comitans of the recipient artery in cases where an incomplete pedal arch was seen on the preoperative angiogram. Statistical analysis Analysis was performed using the Statistica software package (StatSoft, Oklahoma, U.S.A.). Graft patency, patient survival and limb salvage were calculated by the life-table method. Comparisons between patient groups were made using the log-rank test. Results Ail patients previously lost to follow-up attended for Duplex scanning in response to a recall producing a % follow up record. The median time of follow-up was 13 months, ranging from 6 to 36 months. Four patients died during the 30-day postoperative period, three from myocardial infarction and one from multiorgan failure. There were (21%) major complications during the same period; three patients suffered myocardial infarction; three developed renal failure complicating preoperative renal impairment; there were two cases of secondary graft haemorrhage; one patient was successfully resuscitated from a bradycardiac arrest and there was one graft infection necessitating removal of the PTFE.

3 Cuffed PTFE Bypass for Critical Ischaemia 451 For the majority of grafts (46, %) the inflow vessel was the native common femoral artery. In three cases the distal end of a Dacron aorto-biprofunda graft served as inflow and in two cases the distal superficial femoral artery. The commonest outflow vessel was the anterior tibial artery (22, 43%), followed by the posterior tibial artery (19, 37%) and the peroneal artery (, %). Five grafts (9%) took an extra-anatomical course via lateral thigh and lateral Side of the knee joint to reach the anterior tibial artery. Twenty-four grafts (47%) were primary PTFE grafts in patients whose arm and leg veins were of insufficient size, inadequate quality, or had been used for coronary bypass. Twenty-three grafts (45%) were secondary and four (8%) tertiary. Of those patients who survived to 30 days (46, 92%) all had a graft scan at 1 month. Of those 35 who survived a year, 32 (91%) attended for their 12 month scan and of the 16 patients who survived to 2 years, 15 (94%) were scanned. A graft was deemed to be at risk of occluding if there was a doubling of the peak systolic velocity or if the velocity fell below 40 cm/s. During follow-up, 11 grafts (22%) were reported to be at risk for the following reasons: five had low velocities due to run-off disease; two had low velocities due to inflow disease in the external iliac artery; two had low velocities for no identifiable reason and two had significant stenoses just proximal to the vein cuff. The at risk grafts underwent digital subtraction angiography which agreed with the findings of Duplex in all cases. Significant stenoses were treated by balloon angioplasty. Two of the five run-off lesions recurred within 3 months of angioplasty and have needed repeat procedures, two remain non-significant and one graft occluded, but was re-opened by thrombolysis and angioplasty. Unfortunately the graft failed again and the patient underwent above-knee amputation. Neither of the inflow lesions has recurred. Both grafts which had low velocity flow with no identifiable cause subsequently occluded and could not be rescued. In the two cases where a stenosis was found proximal to the cuff, angiography confirmed that the lesion was confluent with the heel of the PTFE to cuff anastomosis. One of these lesions remains non-significant after balloon angioplasty, but the second recurred after 4 months and was successfully treated by vein patch angioplasty. The 1 and 2-year primary patency rates were 64% and 51%, respectively (Fig. 1), compared with secondary patency rates for the same periods of 66% and 52%. Limb salvage figures at 1 and 2 years were 85% and %, respectively (Fig. 2), and patient suvival at those times was 79% and 75% (Fig. 3). Surprisingly, 7o ~ 6o ~ 50 ~ 4o ~ 30 I h z6 --] ~[,I,l,l,l,l,l,l,l,l,l,l,l,I,_ Fig. 1. Kaplan-Meier plot of primary patency. Numbers at risk are?. q ? ~19 21 I ~l,i,i,,i,i~i~i~ili,i~i,ilij Fig. 2. Kaplan-Meier plot of limb salvage. Numbers at risk are ~0 46 ~- 70~ 6O ~ 5o 4 f ~ I~1~ Fig. 3. Kaplan-Meier plot of patient survival. Numbers at risk are diabetes, smoking history, ischaemic heart disease and primary or secondary surgery appeared to have no significant effect on graft patency, limb salvage or survival (Table 2). A distal AVF was constructed in 28 (55%) grafts and

4 452 L.D. Wijesinghe et al. Table 2. Comparison of graft patency, limb salvage and survival according to selected criteria. p value (log rank test) 70 ~ 60 ~ 5o 40 ~ ao ~ 2o Patency Primary vs. secondary 0.92 operation Diabetic vs. not diabetic 0.27 Smoker vs. non smoker 0.31 IHD* vs. no IHD 0.51 IHD = Ischaemic heart disease. 2=~7m 28 ] [ ,J,l~l~f,l,l,l,l,lrlrJ,[,lll, Fig. 4. Kaplan-Meier plot of limb salvage for patients with (+ AVF) and without (-AVF) a distal arteriovenous fistula. The difference between the groups is significant (p = 0.02) by the log-rank test. (--) +AVF; (--) -AVE comparison was made between the AVF and non-avf groups with respect to graft patency, limb salvage and patient survival. There was no significant difference between the groups as far as graft patency (p = 0:96) and survival (p = 0.64) were concerned, but limb salvage appeared to be favoured by the absence of an AVF (p=0.02) (Fig. 4). Four patients required a major amputation during the follow-up period; two below-knee amputations at 1 and 3 days after bypass, and two above-knee amputations at 5 and 15 months. The amputations followed a primary bypass operation in one case, a secondary in two and a tertiary in one. Discussion Femorodistal arterial reconstruction in the absence of autologous vein presents a challenge to both vascular surgeon and patient. There are some who, in the past, have disputed the wisdom of performing a PTFE bypass in these circumstances and have supported a policy of primary amputation. Is However, within the confines of surgery for critical ischaemia, our primary Limb salvage Survival patency rates of 64% at 1 year and 51% at 2 years lend support to the view that PTFE with a distal vein cuff can be used successfully in primary and subsequent femorodistal bypasses if autologous vein is not available. Our patency rates compare favourably with other series of cuffed grafts. Morris reported a 1-year patency of 51% for primary grafts and 44% for secondary and subsequent bypasses; ~6 and Raptis reported 1 and 2- year patencies of 81% and 60%, respectively, for primary grafts, n The patency rates of uncuffed PTFE femorodistal grafts may approach our figures, 3'4 but we remain convinced of the advantages of the vein cuff in assisting a technically better anastomosis, particulary to small vessels, and in preserving the outflow in the event of graft thrombosis, n'17. The graft surveillance programme was able to identify 11 at risk grafts, of which eight remain patent with the help of balloon angioplasty or a vein patch. Clearly angioplasty of inflow, peri-cuff or outflow lesions can extend the life of a failing PTFE graft, and this would be a strong argument in favour of continuing the programme although a formal cost benefit analysis is yet to be performed. The secondary patency at 2 years was 52%, and the limb salvage rate at the same time was %. This difference has been noted before; 3-year patency 43% and limb salvage 71%, 4 4-year patency 38% and limb salvage 70 /o, 3 and may relate to a combination of periarterial sympathectomy performed during vessel dissection; and muscle adaptation and formation of collaterals during the time of a failing graft. The absence of a difference in patency, limb salvage or survival between smokers and non-smokers, and diabetics and non-diabetics, is interesting. The relatively small numbers of patients in each group (13 diabetics, 16 smokers) may explain the failure to detect a difference if there is one. The concept of using an AVF to save ischaemic limbs was first conceived in 12,18 and its beneficial effects on microcirculatory haemodynamics, graft patency and limb salvage have been demonstrated. 19 Harris et ai. 2 suggest that the patency of prosthetic grafts with

5 Cuffed PTFE Bypass for Critical Ischaemia 453 an adjuvant AVF and vein cuff is superior to that of similar grafts with AVF alone. However, we have not been able to demonstrate that the AVF confers any advantage when linked with a vein cuff. Our data appear to show a detrimental effect of AVFs on limb salvage. This may simply be a reflection of the more extensive disease in patients who were selected to have an AVF, because they had an absent pedal arch on angiography. Patients were not randomised to have an AVF, so a meaningful assessment of the role of AVFs cannot be made. This study indicates that femorodistal PTFE grafts have an acceptable patency and limb salvage rate when used in combination with a distal vein cuff for patients with limb-threatening ischaemia. No proof of superiority over an uncuffed graft can be inferred, but evidence from the Joint Vascular Research Group is compelling, at least for below-knee bypasses. The role of an adjuvant AVF may not be clarified without recourse to a randomised trial. Acknowledgements The authors wish to thank Dr M. Weston, Dr D. Kessel and Dr f. Robertson for their help in the graft surveillance programme. References 1 KUNLIN J. Le traitement de l'art6rite oblit6rante par la greffe veineuse. Arch Mal Coeur 1949; 42: HARWARD TRS, COE D, FLYNN TC, SEEGER l M. The use of arm vein conduits during infrageniculate arterial bypass. J Vasc Surg 1992; 16: VEITH FJ, GUPTA KS, ASCER E et al. Six-year prospective multicenter randomised comparison of autologous saphenous vein and expanded polytetrafluoroethylene in infra-inguinal arterial reconstructions. J Vasc Surg 1986; 3: PARSONS RE, SuEts WD, VEITH El et al Polytetrafluoroethylene bypasses to infrapopliteal arteries without cuffs or patches: a better option than amputation in patients without autologous vein. J Vasc Surg 1996; 23: SAUVAGE LR, WALKER MW, BERGER KE et al. Current arterial prostheses: experimental evaluation by implantation in the carotid and circumflex coronary arteries of the dog. Arch Surg 1979; 114: ASCER E, COLLIER Py GUPTA KS, VEITH FJ. Reoperation for polytetrafluoroethylene bypass failure; the importance of distal outflow site and operative technique in determining outcome. J Vasc Surg 1987; s: STERPETTI AV, SCHULTZ RD, FELDHAUS R Iet al. Seven-year experience with polytetrafluoroethylene as above-knee femoropopliteal bypass graft. Is it worthwhile to preserve the autologous saphenous vein? J Vasc Surg 1985; 2: BASSlOUNY HS, WHITE S, GLAGOV S, CHOI E, GIDDENS DP, ZARINS CK. Anastomotic intimal hyperplasia: mechanical or flow induced. J Vasc Surg 1992; 15: KIDSON IG, STONEY DW, TI BS DJ, MORRIS PJ. Expanded polytetrafluoroethylene grafts for severe lower limb ischaemia. Br J Surg 1981; 68: STONEBRIDGE PA, PRESCOTT RP, RUCKLEY CV. Rand0mised trial comparing infrainguinal bypass grafting with and without vein interposition cuff at the distal anastomosis. Br J Surg 1997; 84: RAPTIS S, MILLER JH. Influence of a vein cuff on polytetrafluoroethylene grafts for primary femoropopliteal bypass. Br I Surg 1995; 82: SECOND EUROPEAN CONSENSUS DOCUMENT ON CHRONIC CRIT- ICAL LEG ISCHAEMIA. Eur J Vasc and Endovasc Surg 1992; 6 (Suppl. A): PARKIN A, WIGGINS PA, ROBINSON PJ, VOWDEN Py KESTER RC. The use of a gamma camera for limb blood flow measurements in peripheral vascular disease. Br f Surg 1987; 74: RUTHERFORD RB, FLANIGAN PD, GUPTA SK et al. Suggested standards for reports dealing with lower extremity ischaemia. J Vasc Surg 1986; 4: BELL PRE Are distal vascular procedures worthwhile? Br J Surg 1985; 72: MORRIS GE, RAPTIS S, MILLER JH, FARIS IB. Femorocrural grafting and regrafting: does polytetrafluoroethylene have a role? Cur J Vasc Surg 1993; 7: HARRIS PL. Are vein cuffs worthwhile for PTFE tibial bypasses? In: Veith FJ, ed. Current Critical Problems in Vascular Surgery. St Louis: Quality Medical Publishing Inc., 1994: SAN MARTIN Y SATRUSTEGUI a. Anastomose arterio-veineuse peut remedier a obliteration des arteres des membres. Bull Med 12; 16: JACOBS MJHM, REUL GJ, GREGORIC ID, UBBINK DT, TORDOIR JHM, KITSLAAR PJEHM, RENEMAN RS. Creation of a distal arteriovenous fistula improves microcirculatory hemodynamics of prosthetic graft bypass in secondary limb salvage procedures. ] Vasc Surg 1993; 18: 1-9. HARRIS PL, BAKRAN A, ENABI L, NOTT DM. EPTFE grafts for femorocrural bypass - improved results with combined adjuvant venous cuff and arteriovenous fistula. Eur J Vasc Surg 1993; 7: Accepted 15 January 1998